Skill Order

Champion Matchups

Introduction

Olaf is one of the strongest champions in early game imo.

Olaf is strong early game with his axes and true damage. Stay farming and throw the axes on the enemy. at lvl 2 you can throw axes and use true damage. Make sure all the time picking up the axe if you can, it will only be 1-2 second/s cooldown on it, and you can pick up easy kills in the start since axes are slowing alot. using exhaust will really secure the kill.

Capture the altars so often you can, and try to always kill Vilemaw, it is worth 190g and gives you a buff that grants bonus stuff

Masteries

I have 9-21-0 in masteries, but you can also switch to 0-21-9 depending what you prefer, i prefer 9-21-0.
Because it gives me some of sustain and "tankyness" So... You just got tanked! if you go 0-21-9 it will give you even more sustain and tankyness.

Early game

Early game. Max your E (true damage) since it does alot of damage. your Q (axes) are used for slows.
your W will increase your attack damage depending how much extra hp you got from items, and it will give you lifesteal. Throw your axe and use your true damage when close enough and repeat doing that. Use a basic attack sometimes. Some firstblood plans are great, Olaf can throw an axe to slow down an enemy and deal alot of damage if it hits all their team. So i'd reccomend you to figure out a firstblood-plan. you can camp in the bush near the movement speed bonus, or at your altar, make sure whole your team is there.
Take vilemaw when your team are ready, and make sure your enemy team is far away

Mid game

Mid game. try to stick with your team and go for freekills, etc one of their teammate is outposistioned, example pushing your turret, make sure it is not a bait. I dont reccomend you to use ulti to get away, unless you are the only one in your team alive, you must defend turrets. Engage the teamfights and use your ulti for more armor and magic resist, which is very much at lvl 16.

Late game

Keep up your farming, stick with your team. go for freekills and capture the altars for bonus gold ap and ad. Vilemaw gives you a buff and 190g so make sure killing it before your enemy does.
Focus the enemy dealing the most damage, leave the tank till the last.

Final Comments

Olaf have very good sustain and is very tanky, he is a great farmer. And a great resource for your team.
Vilemaw and the altars are very important, always try controlling the altars and killing Vilemaw

Comments

You are missing a couple of key sections for an approved guide. Explanations of runes, teamfights sections, did not explain skills, did not talk about your items, you only listed them. You can add a lane matchups chapter since that pretty much goes above and beyond. Adding those sections will really help your guide.